JP7626046B2 - Leak Diagnostic Device - Google Patents

Description

The present invention relates to a leak diagnosis device.

The fuel supply mechanism of Patent Document 1 includes a fuel tank, a vapor passage, a canister, an outside air passage, a shutoff valve, and a pump. The fuel tank stores fuel. The canister is connected to the fuel tank via the vapor passage. The canister is capable of absorbing evaporated fuel generated in the fuel tank. The outside air passage is connected to the canister. The shutoff valve is located midway through the vapor passage. The shutoff valve opens and closes the flow path of the vapor passage. The pump is capable of discharging gas inside the canister.

The leak diagnosis device of Patent Document 1 executes a diagnostic process while the internal combustion engine is stopped, on the condition that the amount of evaporated fuel adsorbed in the canister is equal to or less than a predetermined threshold. Specifically, as part of the diagnostic process, the leak diagnosis device uses a pump to discharge gas from inside the fuel tank with the shutoff valve open. At this time, the leak diagnosis device diagnoses the presence or absence of gas leakage from the fuel tank based on changes in pressure inside the fuel tank.

JP 2010-216287 A

Depending on the operating conditions of the internal combustion engine, the amount of evaporated fuel adsorbed in the canister may exceed a threshold value for a long period of time. In this case, the leak diagnosis device of Patent Document 1 cannot perform the diagnosis process for a long period of time. In other words, the leak diagnosis device of Patent Document 1 may have an excessively low frequency of execution of the diagnosis process. If the frequency of execution of the diagnosis process is low, it is not possible to determine the presence or absence of gas leakage from the fuel tank for a long period of time, which is undesirable.

The leak diagnosis device for solving the above problem diagnoses a fuel supply mechanism that includes a fuel tank for storing fuel, a vapor passage connected to the fuel tank, a canister connected to the vapor passage and capable of absorbing evaporated fuel generated in the fuel tank, an outside air passage connected to the canister, a shutoff valve for opening and closing the flow path of the vapor passage, and a pump capable of discharging gas inside the canister through the outside air passage, and performs a judgment process for judging whether the amount of evaporated fuel absorbed in the canister is equal to or less than a predetermined threshold value, and a judgment result of the judgment process is positive. With this as one of the conditions, it is possible to execute a discharge process in which the pump discharges gas from inside the fuel tank with the shutoff valve open, a diagnosis process in which the presence or absence of a gas leak from the fuel tank is diagnosed based on the change in pressure inside the fuel tank during the discharge process, and a normal diagnosis process in which, when the pressure inside the fuel tank is outside a predetermined range that is equal to or greater than a value lower than atmospheric pressure by a predetermined first specified value and equal to or less than a value higher than atmospheric pressure by a predetermined second specified value, the system is capable of executing a normal diagnosis process that diagnoses that there is no gas leak in the fuel tank without relying on the discharge process and the diagnosis process.

According to the above configuration, if the pressure inside the fuel tank is outside the predetermined range, that is, if the pressure inside the fuel tank deviates from the atmospheric pressure and it can be estimated that there is no gas leakage in the fuel tank, it is diagnosed that there is no gas leakage in the fuel tank. This makes it possible to prevent a prolonged state in which it is unclear whether or not there is a gas leak in the fuel tank.

1 is a schematic diagram showing a schematic configuration of a vehicle. FIG. 1 is a diagram showing a configuration of an internal combustion engine, etc. 4 is a flowchart showing a leak diagnosis control.

<General configuration of the vehicle>
An embodiment of the present invention will now be described with reference to Figures 1 to 3. First, a schematic configuration of a vehicle 100 will be described.

As shown in FIG. 1, the vehicle 100 is equipped with a spark-ignition internal combustion engine 10. The vehicle 100 is also equipped with a first motor generator 71 and a second motor generator 72 that function as both an electric motor and a generator. Therefore, the vehicle 100 is a so-called hybrid vehicle. In this embodiment, the internal combustion engine 10, the first motor generator 71, and the second motor generator 72 are all drive sources for the vehicle 100.

The vehicle 100 includes a first planetary gear mechanism 40 , a ring gear shaft 45 , a second planetary gear mechanism 50 , a reduction mechanism 62 , a differential mechanism 63 , and a plurality of drive wheels 64 .
The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to the first motor generator 71. The ring gear 42 is an internal gear and is located coaxially with the sun gear 41. Each pinion gear 43 is located between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gear 43. The pinion gear 43 is rotatable on its own axis and is revolvable by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 14 of the internal combustion engine 10. Therefore, the first motor generator 71 is connected to the crankshaft 14 of the internal combustion engine 10 via the first planetary gear mechanism 40.

When the driving force of the internal combustion engine 10 is input to the carrier 44, the driving force of the internal combustion engine 10 is distributed to the sun gear 41 side and the ring gear 42 side. Then, when the driving force of the internal combustion engine 10 transmitted via the sun gear 41 is input to the rotating shaft of the first motor generator 71, the first motor generator 71 functions as a generator.

On the other hand, when the first motor generator 71 is made to function as an electric motor, the driving force of the first motor generator 71 is input to the sun gear 41. The driving force of the first motor generator 71 input to the sun gear 41 is then distributed to the carrier 44 side and the ring gear 42 side. Then, when the driving force of the first motor generator 71 transmitted via the carrier 44 is input to the crankshaft 14 of the internal combustion engine 10, the crankshaft 14 of the internal combustion engine 10 rotates.

The ring gear shaft 45 is connected to the ring gear 42. The ring gear shaft 45 is also connected to the drive wheels 64 via a reduction mechanism 62 and a differential mechanism 63. The reduction mechanism 62 reduces the rotational speed of the ring gear shaft 45 and outputs it. The differential mechanism 63 allows a difference in rotational speed to occur between the left and right drive wheels 64.

The second planetary gear mechanism 50 includes a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gear 53. The pinion gear 53 is rotatable. The carrier 54 is fixed to the case 55. Therefore, the pinion gear 53 is in a state where it cannot revolve.

The second motor generator 72 functions as a generator when decelerating the vehicle 100, thereby generating a regenerative braking force in the vehicle 100 that corresponds to the amount of power generated by the second motor generator 72.

On the other hand, when the second motor generator 72 is made to function as an electric motor, the driving force of the second motor generator 72 is input to the driving wheels 64 via the second planetary gear mechanism 50, the ring gear shaft 45, the reduction mechanism 62, and the differential mechanism 63. Then, the driving force of the second motor generator 72 rotates the driving wheels 64.

The vehicle 100 is equipped with a battery 75, a first inverter 76, and a second inverter 77. The first inverter 76 performs AC/DC power conversion between the first motor generator 71 and the battery 75. The first inverter 76 also adjusts the amount of power exchanged between the first motor generator 71 and the battery 75. The second inverter 77 performs AC/DC power conversion between the second motor generator 72 and the battery 75. The second inverter 77 adjusts the amount of power exchanged between the second motor generator 72 and the battery 75.

<Configuration of the internal combustion engine>
As shown in FIG. 2, the internal combustion engine 10 includes a plurality of cylinders 11, an intake passage 15, and an exhaust passage 21. Each cylinder 11 is a space in which a mixture of fuel and intake air is burned. The internal combustion engine 10 includes four cylinders 11. Note that FIG. 2 illustrates only one cylinder 11. An intake passage 15 is connected to each cylinder 11. The intake passage 15 introduces intake air from outside the internal combustion engine 10 into the cylinders 11. An exhaust passage 21 is connected to each cylinder 11. The exhaust passage 21 discharges exhaust gas from the cylinders 11 to outside the internal combustion engine 10.

The internal combustion engine 10 includes a plurality of pistons 12, a plurality of connecting rods 13, a crankshaft 14, a throttle valve 16, a plurality of fuel injection valves 17, and a plurality of ignition devices 19. The throttle valve 16 is located in the intake passage 15. The throttle valve 16 adjusts the amount of intake air flowing through the intake passage 15. The fuel injection valve 17 is located in the intake passage 15 near the cylinder 11. The internal combustion engine 10 includes four fuel injection valves 17 corresponding to the four cylinders 11. The fuel injection valve 17 injects fuel toward the cylinder 11. The ignition device 19 is located near the cylinder 11. The internal combustion engine 10 includes four ignition devices 19 corresponding to the four cylinders 11. The ignition device 19 ignites the mixture of fuel and intake air by spark discharge.

The pistons 12 are located in the cylinders 11. The internal combustion engine 10 has four pistons 12 corresponding to the four cylinders 11. The pistons 12 are connected to a crankshaft 14 via connecting rods 13. The pistons 12 reciprocate in association with the combustion of a mixture of fuel and intake air in the cylinders 11. The reciprocating movement of the pistons 12 causes the crankshaft 14 to rotate.

<Configuration of fuel supply mechanism>
The vehicle 100 further includes a fuel supply mechanism 25. The fuel supply mechanism 25 includes a fuel tank 26, a feed pump 27, a fuel passage 28, and a lid door 29. The fuel tank 26 includes a tank body 26A and a cap 26C. The tank body 26A can store fuel. The tank body 26A includes a fuel filler port 26B for supplying fuel to the tank body 26A. The cap 26C closes the fuel filler port 26B of the tank body 26A. The cap 26C is detachable from the tank body 26A. The feed pump 27 is located in the tank body 26A of the fuel tank 26. The feed pump 27 is connected to the fuel injection valve 17 via the fuel passage 28. Therefore, the feed pump 27 supplies fuel to the fuel injection valve 17 via the fuel passage 28. The lid door 29 constitutes a part of the outer surface of the vehicle 100. The lid door 29 is located near the cap 26C. The lid door 29 can be opened and closed by an operation of the driver, etc. When the lid door 29 is in a closed state, the lid door 29 covers the cap 26C.

The fuel supply mechanism 25 includes a vapor passage 31, a canister 32, an outside air passage 33, a purge passage 34, a shutoff valve 36, an outside air valve 37, a purge valve 38, and a pump module 39. The canister 32 is capable of absorbing evaporated fuel generated in the fuel tank 26. A first end of the vapor passage 31 is connected to the canister 32. A second end of the vapor passage 31 is located inside the fuel tank 26. The shutoff valve 36 is located midway through the vapor passage 31. The shutoff valve 36 switches the flow path of the vapor passage 31 between an open state and a closed state. The shutoff valve 36 is a normally closed solenoid valve.

The first end of the outside air passage 33 is connected to the canister 32. The second end of the outside air passage 33 is open to the outside of the vehicle 100. The outside air valve 37 is located in the middle of the outside air passage 33. The outside air valve 37 switches the flow path of the outside air passage 33 to either an open state or a closed state. The outside air valve 37 is a normally open solenoid valve. The pump module 39 is located in the middle of the outside air passage 33. The pump module 39 is connected to the outside air valve 37. The pump module 39 can discharge gas in the canister 32 to the outside via the outside air passage 33. The pump module 39 can also discharge gas in the fuel tank 26 to the outside via the vapor passage 31, the canister 32, and the outside air passage 33. In this embodiment, the pump module 39 is an example of a pump.

A first end of the purge passage 34 is connected to the canister 32. A second end of the purge passage 34 is connected to a portion of the intake passage 15 that is downstream from the throttle valve 16. The purge valve 38 is located midway through the purge passage 34. The purge valve 38 is capable of adjusting the opening degree of the flow path of the purge passage 34. The purge valve 38 is a normally closed solenoid valve.

<Configuration of sensor and control device>
As shown in FIG. 2, the vehicle 100 includes an accelerator operation amount sensor 81, a vehicle speed sensor 82, a tank internal pressure sensor 83, a lid sensor 84, a liquid level sensor 86, an atmospheric pressure sensor 87, a pressure sensor 88, and a display 89. The accelerator operation amount sensor 81 detects an accelerator operation amount ACC, which is an operation amount of the accelerator pedal operated by the driver. The vehicle speed sensor 82 detects a vehicle speed SP, which is the speed of the vehicle 100. The tank internal pressure sensor 83 is attached to the upper part of the fuel tank 26. The tank internal pressure sensor 83 detects a tank internal pressure PT, which is the pressure inside the fuel tank 26. The lid sensor 84 detects an opening/closing position LS, which is the position of the lid door 29. The liquid level sensor 86 is located inside the fuel tank 26. The liquid level sensor 86 detects a liquid level FL, which is the position of the liquid level of the fuel inside the fuel tank 26. The atmospheric pressure sensor 87 detects an atmospheric pressure PA, which is the pressure of the atmosphere at the point where the vehicle 100 is located. The pressure sensor 88 is located inside the pump module 39. The pressure sensor 88 detects a flow path pressure PX, which is the pressure of the flow path in the pump module 39. The display 89 is located near the driver's seat of the vehicle 100. The display 89 displays visual information to the driver of the vehicle 100, etc.

The vehicle 100 is equipped with a control device 90. The control device 90 obtains a signal indicating the accelerator operation amount ACC from the accelerator operation amount sensor 81. The control device 90 obtains a signal indicating the vehicle speed SP from the vehicle speed sensor 82. The control device 90 obtains a signal indicating the tank internal pressure PT from the tank internal pressure sensor 83. The control device 90 obtains a signal indicating the open/close position LS from the lid sensor 84. The control device 90 obtains a signal indicating the liquid level FL from the liquid level sensor 86. That is, the control device 90 can detect the amount of fuel in the fuel tank 26 and the amount of fuel supplied to the fuel tank 26 based on the liquid level FL. The control device 90 obtains a signal indicating the atmospheric pressure PA from the atmospheric pressure sensor 87. The control device 90 obtains a signal indicating the flow path pressure PX from the pressure sensor 88. The control device 90 outputs a control signal to the display 89 to display visual information on the display 89.

The control device 90 calculates the vehicle required driving force, which is the required value of the driving force required for the vehicle 100 to travel, based on the accelerator operation amount ACC and the vehicle speed SP. The control device 90 determines the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72 based on the vehicle required driving force. The control device 90 controls the output of the internal combustion engine 10 and the power running and regeneration of the first motor generator 71 and the second motor generator 72 based on the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72. Specifically, the control device 90 controls the opening degree of the throttle valve 16, the fuel injection amount from the fuel injection valve 17, the ignition timing of the ignition device 19, etc., by outputting a control signal to the internal combustion engine 10. The control device 90 also controls the first motor generator 71 via the first inverter 76 by outputting a control signal to the first inverter 76. Furthermore, the control device 90 controls the second motor generator 72 via the second inverter 77 by outputting a control signal to the second inverter 77.

The control device 90 executes introduction control to introduce the evaporated fuel adsorbed in the canister 32 into the intake passage 15 while the internal combustion engine 10 is running. Specifically, the control device 90 opens the shutoff valve 36, the outside air valve 37, and the purge valve 38 while the internal combustion engine 10 is running. Then, due to the negative pressure in the intake passage 15, outside air is introduced into the canister 32 via the outside air passage 33. As a result, the evaporated fuel adsorbed in the canister 32 and the outside air are introduced into the intake passage 15 via the purge passage 34.

The control device 90 also calculates the purge amount, which is the amount of evaporated fuel introduced from the canister 32 to the intake passage 15 per unit time by the introduction control. The control device 90 then calculates the accumulated purge amount SAM by accumulating the purge amount during the period from when fuel is refueled in the fuel tank 26 until the next refueling. Furthermore, the control device 90 calculates the amount of evaporated fuel adsorption CX in the canister 32 based on the accumulated purge amount SAM. Specifically, the larger the accumulated purge amount SAM, the smaller the value of the adsorption amount CX that the control device 90 calculates.

When refueling the fuel tank 26, the control device 90 executes preparation control to prepare for refueling. Specifically, the control device 90 detects the state of the lid door 29 based on the open/close position LS. Then, when the control device 90 detects that the lid door 29 is in the open state, it closes the purge valve 38 and opens the shutoff valve 36 and the outside air valve 37. Then, when refueling the fuel tank 26, gas in the fuel tank 26 can move from the fuel tank 26 to the canister 32. As a result, when refueling the fuel tank 26, gas in the fuel tank 26 is prevented from being discharged to the outside from the fuel filler port 26B of the fuel tank 26.

The control device 90 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 90 may also be configured as a circuit including one or more dedicated hardware circuits, such as application specific integrated circuits (ASICs), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any medium that can be accessed by a general-purpose or dedicated computer.

<Leak diagnosis control>
Next, a description will be given of the leak diagnosis control performed by the control device 90. In this embodiment, the control device 90 is an example of a leak diagnosis device. The control device 90 executes the leak diagnosis control only once each time either of the following two conditions is satisfied.

Condition (A): Leak diagnosis control has not been performed since the internal combustion engine 10 was stopped, and the period of time since the internal combustion engine 10 was stopped is equal to or longer than a predetermined period of time. An example of the predetermined period of time is several hours.

Condition (B): Leak diagnosis control has been performed since the internal combustion engine 10 was stopped, the previous leak diagnosis control diagnosed that there was no gas leakage from the canister 32 and the fuel tank 26, and the time that has elapsed since the previous diagnosis was completed is equal to or longer than a predetermined period of time.

As shown in FIG. 3, when the control device 90 starts the leak diagnosis control, it proceeds to the process of step S11. In step S11, the control device 90 judges whether the tank internal pressure PT is outside a predetermined range. Here, the predetermined range is a range that is at least a value lower than the atmospheric pressure PA at the time of processing in step S11 by a predetermined first specified value and is at most a value higher than the atmospheric pressure PA at the time of processing in step S11 by a predetermined second specified value. An example of the first specified value is several kPa. An example of the second specified value is several kPa. The first specified value and the second specified value may be the same value or different values. In step S11, when the control device 90 judges that the tank internal pressure PT is within the predetermined range (S11: NO), it proceeds to the process of step S13.

In step S13, the control device 90 sets a predetermined first reference value as the threshold value A. Here, the first reference value is determined, for example, as follows. In the leak diagnosis control, when the first discharge process and the second discharge process described below are performed, the amount of evaporated fuel adsorption CX in the canister 32 increases due to the movement of gas containing evaporated fuel. Therefore, when both the first discharge process and the second discharge process are performed, the maximum amount of evaporated fuel flowing into the canister 32 is obtained by experiment or the like. Then, the value obtained by subtracting the maximum amount of evaporated fuel flowing into the canister 32 from the limit value of the amount of adsorption CX that the canister 32 can adsorb is determined as the first reference value. After that, the control device 90 advances the process to step S21.

On the other hand, in step S11, when the control device 90 determines that the tank internal pressure PT is outside the predetermined range (S11: YES), the control device 90 proceeds to step S12.
In step S12, the control device 90 sets a second reference value determined in advance as the threshold value A. Here, the second reference value is determined, for example, as follows. First, the maximum amount of evaporated fuel flowing into the canister 32 when only the first discharge process in the leak diagnosis control is executed is obtained by experiment or the like. Then, the second reference value is determined by subtracting the maximum amount of evaporated fuel flowing into the canister 32 from the limit value of the adsorption amount CX that the canister 32 can adsorb. In this way, the second reference value is a value that takes into account the amount of evaporated fuel when only the first discharge process is executed without executing the second discharge process, so the second reference value is a value larger than the first reference value. Therefore, when the tank internal pressure PT is outside the predetermined range, the control device 90 sets the threshold value A to a value larger than when the tank internal pressure PT is within the predetermined range. In this embodiment, the processes of steps S11 to S13 can be said to be threshold value changing processes that set the threshold value A to a value larger than when the pressure inside the fuel tank 26 is outside the predetermined range. Thereafter, the control device 90 advances the process to step S21.

In step S21, the control device 90 determines whether the amount of adsorption CX is equal to or less than a predetermined threshold value A. In this embodiment, the process of step S21 corresponds to a determination process. In step S21, if the control device 90 determines that the amount of adsorption CX is greater than the threshold value A (S21: NO), the control device 90 ends the current leak diagnosis control. On the other hand, in step S21, if the control device 90 determines that the amount of adsorption CX is equal to or less than the threshold value A (S21: YES), the control device 90 advances the process to step S31. That is, the control device 90 advances the process from step S31 onward, taking the positive determination result in the determination process in step S21 as one of the conditions.

In step S31, the control device 90 executes a first discharge process for discharging gas from the inside of the canister 32 for a predetermined first period. Specifically, the control device 90 closes the purge valve 38 and the shutoff valve 36, while opening the outside air valve 37. The control device 90 then uses the pump module 39 to discharge the gas from the inside of the canister 32 to the outside through the outside air passage 33. At this time, even if the gas contains evaporated fuel, the evaporated fuel is adsorbed by the canister 32, so that the gas containing evaporated fuel is prevented from being discharged to the outside. An example of the first period is several minutes. In other words, the first discharge process is a process for discharging gas from the inside of the canister 32 by the pump module 39 with the shutoff valve 36 closed. The control device 90 then advances the process to step S32.

In step S32, the control device 90 acquires the flow path pressure PX at the time when the first period has elapsed since the start of the first discharge process as the canister internal pressure PC. Then, the control device 90 judges whether the canister internal pressure PC is equal to or less than a predetermined judgment value B. Here, the judgment value B is determined as follows. First, if there is no gas leakage in the canister 32, the first discharge process in step S31 is executed, and the canister internal pressure PC at the time when the first period has elapsed since the start of the first discharge process becomes equal to or less than a certain value. On the other hand, if there is gas leakage in the canister 32 due to a crack in the canister 32, even if the first discharge process in step S31 is executed, the canister internal pressure PC at the time when the first period has elapsed since the start of the first discharge process does not become equal to or less than a certain value. Therefore, the above-mentioned constant value is obtained by an experiment or the like. Then, the above-mentioned constant value is determined as the judgment value B.

In step S32, if the control device 90 determines that the canister internal pressure PC is equal to or lower than the judgment value B (S32: YES), the process proceeds to step S33. In step S33, the control device 90 diagnoses that there is no gas leak in the canister 32, i.e., that the canister 32 is normal. Thereafter, the control device 90 proceeds to step S41.

On the other hand, in step S32, if the control device 90 determines that the canister internal pressure PC is higher than the judgment value B (S32: NO), the process proceeds to step S34. In step S34, the control device 90 diagnoses that there is a gas leak in the canister 32, i.e., that the canister 32 is abnormal. In the following, the processes in steps S32 to S34 are collectively referred to as the first diagnostic process. In other words, the first diagnostic process is a process for diagnosing the presence or absence of a gas leak in the canister 32 based on the change in the pressure inside the canister 32 during the above-mentioned first discharge process. In addition, the control device 90 outputs a control signal to the display 89, thereby notifying the driver or the like via the display 89 that the canister 32 is abnormal. Thereafter, the control device 90 proceeds to step S41.

In step S41, the control device 90 determines whether the tank internal pressure PT is outside a predetermined range. The process of step S41 is the same as the process of step S11. In step S41, if the control device 90 determines that the tank internal pressure PT is outside the predetermined range (S41: YES), the process proceeds to step S42.

In step S42, the control device 90 diagnoses that there is no gas leak in the fuel tank 26, i.e., that the fuel tank 26 is normal. In other words, when the tank internal pressure PT is outside the predetermined range, the control device 90 diagnoses that there is no gas leak in the fuel tank 26, i.e., that the fuel tank 26 is normal, without relying on the processing of steps S51 to S54 described below. In this embodiment, the processing of steps S41 to S42 corresponds to normal diagnosis processing. Thereafter, the control device 90 ends the current leak diagnosis control.

In step S41, when the control device 90 determines that the tank internal pressure PT is within the predetermined range (S41: NO), the control device 90 advances the process to step S51.
In step S51, the control device 90 executes a second discharge process for discharging gas in the fuel tank 26 for a second predetermined period. Specifically, the control device 90 closes the purge valve 38 and opens the shutoff valve 36 and the outside air valve 37. Then, the control device 90 discharges gas in the fuel tank 26 to the outside through the vapor passage 31, the canister 32, and the outside air passage 33 by the pump module 39. At this time, even if the gas contains evaporated fuel, the evaporated fuel is adsorbed by the canister 32, so that the gas containing evaporated fuel is prevented from being discharged to the outside. An example of the second period is several tens of minutes. In other words, the second discharge process is a process for discharging gas in the fuel tank 26 by the pump module 39 with the shutoff valve 36 open. In this embodiment, the second discharge process corresponds to a discharge process. Thereafter, the control device 90 advances the process to step S52.

In step S52, the control device 90 acquires the tank internal pressure PT at the time when the second period has elapsed since the start of the second discharge process. Then, the control device 90 judges whether the tank internal pressure PT is equal to or lower than a predetermined judgment value C. Here, the judgment value C is determined as follows. First, if there is no gas leakage in the fuel tank 26, the second discharge process in step S51 is executed, so that the tank internal pressure PT at the time when the second period has elapsed since the start of the second discharge process becomes equal to or lower than a certain value. On the other hand, if there is gas leakage in the fuel tank 26 due to a crack in the fuel tank 26, even if the second discharge process in step S51 is executed, the tank internal pressure PT at the time when the second period has elapsed since the start of the second discharge process does not become equal to or lower than a certain value. Therefore, the above-mentioned constant value is obtained by an experiment or the like. Then, the above-mentioned constant value is determined as the judgment value C. In this embodiment, the judgment value C is the same as the judgment value B.

In step S52, if the control device 90 determines that the tank internal pressure PT is equal to or lower than the judgment value C (S52: YES), the process proceeds to step S53. In step S53, the control device 90 diagnoses that there is no gas leak in the fuel tank 26, i.e., that the fuel tank 26 is normal. The control device 90 then ends the current leak diagnosis control.

On the other hand, in step S52, if the control device 90 determines that the tank internal pressure PT is higher than the judgment value C (S52: NO), the process proceeds to step S54. In step S54, the control device 90 diagnoses that there is a gas leak in the fuel tank 26, that is, that the fuel tank 26 is abnormal. In the following, the processes in steps S52 to S54 are collectively referred to as the second diagnosis process. In other words, the second diagnosis process is a process for diagnosing the presence or absence of a gas leak in the fuel tank 26 based on the change in the pressure inside the fuel tank 26 during the second discharge process. In this embodiment, the second diagnosis process corresponds to the diagnosis process. In addition, the control device 90 outputs a control signal to the display 89 to notify the driver or the like that the fuel tank 26 is abnormal via the display 89. Thereafter, the control device 90 ends the current leak diagnosis control.

<Action of this embodiment>
When refueling the fuel tank 26, the cap 26C is removed from the fuel inlet 26B of the tank body 26A, so that the inside and outside of the fuel tank 26 are connected via the fuel inlet 26B. Therefore, immediately after refueling the fuel tank 26, the tank internal pressure PT becomes approximately the same as the atmospheric pressure PA. On the other hand, after refueling, if there is no abnormality such as a crack in the fuel tank 26, the tank internal pressure PT may become higher than the atmospheric pressure PA due to, for example, the generation of evaporated fuel inside the fuel tank 26. Also, for example, the tank internal pressure PT may become lower than the atmospheric pressure PA due to temperature changes in the fuel tank 26 and the outside air. Therefore, after refueling, if there is no abnormality such as a crack in the fuel tank 26, the tank internal pressure PT tends to deviate from the atmospheric pressure PA. In other words, the tank internal pressure PT may become outside the predetermined range while the vehicle 100 is stopped. Also, such a phenomenon is not rare, and occurs with considerable frequency while the vehicle 100 is stopped.

<Effects of this embodiment>
(1) When the tank internal pressure PT is outside the predetermined range, the control device 90 diagnoses that there is no abnormality in the fuel tank 26 without relying on the second discharge process and the second diagnosis process. In other words, when the tank internal pressure PT deviates from the atmospheric pressure PA and it can be estimated that there is no gas leakage in the fuel tank 26, the control device 90 diagnoses that there is no abnormality in the fuel tank 26 without relying on the second discharge process and the second diagnosis process. This makes it possible to prevent a prolonged state in which it is unclear whether or not there is a gas leak in the fuel tank 26.

(2) When the tank internal pressure PT is outside the predetermined range, i.e., when the second discharge process and the second diagnostic process are not executed, the control device 90 increases the threshold value A. This makes it easier to determine that the adsorption amount CX is equal to or less than the threshold value A, and therefore increases the frequency with which the first discharge process and the first diagnostic process are executed. As a result, it is possible to prevent a prolonged state in which it is unclear whether or not a gas leak is occurring in the canister 32.

When the tank internal pressure PT is outside the predetermined range, the second discharge process is not executed, so that evaporated fuel does not flow into the canister 32 due to the execution of the second discharge process. This makes it possible to prevent a situation in which the canister 32 is unable to adsorb evaporated fuel, even if a high value is set as the threshold A.

(3) In this embodiment, if the tank internal pressure PT is outside the predetermined range, the second discharge process is not executed, and the fuel tank 26 is diagnosed as having no abnormality. Therefore, when diagnosing the presence or absence of a gas leak in the fuel tank 26, energy to drive the pump module 39 is not required. In addition, the presence or absence of a gas leak in the fuel tank 26 can be determined without requiring time for the pump module 39 to discharge the gas inside the fuel tank 26.

<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

In the above embodiment, the execution condition of the leak diagnosis control may be changed. For example, the following condition (A) may be adopted. Similarly, the condition (B) may be changed.
Condition (A): Leak diagnosis control has not been performed since the internal combustion engine 10 was stopped, the period of time that has elapsed since the internal combustion engine 10 was stopped is greater than or equal to a predetermined period of time, and the temperature of the cooling water flowing inside the internal combustion engine 10 is less than or equal to a specified temperature.

In the leak diagnosis control of the above embodiment, the predetermined ranges of step S11 and step S41 may be changed.
For example, the predetermined range in step S11 may be set with respect to the standard atmospheric pressure. In other words, the predetermined range in step S11 may be a range from a value lower than the standard atmospheric pressure by a predetermined first specified value to a value higher than the standard atmospheric pressure by a predetermined second specified value. In this case, the lower limit value and the upper limit value of the predetermined range are fixed values. Similarly, the predetermined range in step S41 may be changed.

- In the leak diagnosis control of the above embodiment, the processes of steps S11 to S13 may be omitted. Even with this configuration, if the tank internal pressure PT is outside the predetermined range, it can be diagnosed that there is no abnormality in the fuel tank 26 without relying on the second discharge process and the second diagnosis process.

- In the leak diagnosis control of the above embodiment, the processes of steps S31 to S34 may be omitted. Even with this configuration, the processes of steps S41 to S54 can prevent the continuation of a state in which it is unclear whether or not a gas leak has occurred in the fuel tank 26. Note that in the second discharge process in step S51, the pump module 39 discharges gas in the fuel tank 26 to the outside via the canister 32. Therefore, if the processes of steps S41 to S54 diagnose that there is no gas leak in the fuel tank 26, it may be diagnosed that there is no gas leak in the fuel tank 26 and the canister 32.

In the leak diagnosis control of the above embodiment, the process of step S52 may be modified.
For example, in step S52, the control device 90 may determine whether the flow path pressure PX at the time when the second period has elapsed since the start of the second discharge process is equal to or lower than a determination value C. Also, for example, the determination value C may be different from the determination value B.

- In the above embodiment, the vehicle 100 does not have to be equipped with the first motor generator 71 and the second motor generator 72. In other words, if the vehicle 100 is equipped with an internal combustion engine 10 and the leak diagnosis device diagnoses the fuel supply mechanism 25 that supplies fuel to the internal combustion engine 10, the present technology can be applied.

10... internal combustion engine 25... fuel supply mechanism 26... fuel tank 29... lid door 31... vapor passage 32... canister 33... outside air passage 34... purge passage 36... shutoff valve 37... outside air valve 38... purge valve 39... pump module 40... first planetary gear mechanism 45... ring gear shaft 50... second planetary gear mechanism 62... reduction mechanism 63... differential mechanism 64... drive wheel 71... first motor generator 72... second motor generator 81... accelerator operation amount sensor 82... vehicle speed sensor 83... tank internal pressure sensor 84... lid sensor 86... liquid level sensor 87... atmospheric pressure sensor 88... pressure sensor 89... display 90... control device 100... vehicle

Claims (1)

A fuel tank for storing fuel;
a vapor passage connected to the fuel tank;
a canister connected to the vapor passage and capable of absorbing evaporated fuel generated in the fuel tank;
an outside air passage connected to the canister;
a shutoff valve that opens and closes a flow path of the vapor passage;
a pump capable of discharging gas inside the canister through the outside air passage;
The fuel supply mechanism to be diagnosed is provided with
a determination process for determining whether or not an amount of vaporized fuel adsorbed in the canister is equal to or less than a predetermined threshold;
a discharge process for discharging gas from inside the fuel tank by the pump with the shutoff valve open, on the condition that a result of the determination process is positive;
a diagnosis process for diagnosing the presence or absence of a gas leak from the fuel tank based on a change in pressure inside the fuel tank during the discharge process;
a normal diagnosis process for diagnosing that there is no gas leakage from the fuel tank without relying on the discharge process and the diagnosis process, when the pressure inside the fuel tank is outside a predetermined range defined as a range of a value lower than atmospheric pressure by a first specified value and a value higher than atmospheric pressure by a second specified value;
A leak diagnostic device that is capable of

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